﻿
// 遮罩纹理
Shader "Custom/Chapter 7/MaskTexture" {
	Properties {
		_Color ("Color", Color) = (1,1,1,1)
		_MainTex ("Main Tex", 2D) = "white" {}
		_BumpMap ("Bump Map", 2D) = "bump" {}
		_BumpScale ("Bump Scale",Float) = -0.5
		_SpecularMask ("Specular Mask",2D) = "white" {}		// 高光反射遮罩
		_SpecularScale ("Specular Scale",Float) = 1.0		// 遮罩影响度系数
		_Specular ("Specular",Color) = (1,1,1,1)
		_Gloss ("Gloss",Range(8.0,256)) = 20
	}
	SubShader {
		Pass {
			Tags { "LightMode"="ForwardBase" }
		
			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag

			#include "Lighting.cginc"

			fixed4 _Color;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			sampler2D _BumpMap;
			float4 _BumpMap_ST;
			float _BumpScale;
			sampler2D _SpecularMask;
			float _SpecularScale;
			fixed4 _Specular;
			float _Gloss;

			struct a2v {
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 tangent : TANGENT;
				float4 texcoord : TEXCOORD0;
			};

			struct v2f {
				float4 pos : SV_POSITION;
				float2 uv : TEXCOORD0;
				float3 lightDir : TEXCOORD1;
				float3 viewDir : TEXCOORD2;
			};

			v2f vert(a2v v) {
				v2f o;
				o.pos = UnityObjectToClipPos(v.vertex);

				o.uv.xy = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;

				TANGENT_SPACE_ROTATION;
				o.lightDir = mul(rotation,ObjSpaceLightDir(v.vertex)).xyz;
				o.viewDir = mul(rotation,ObjSpaceViewDir(v.vertex)).xyz;

				return o;
			}

			fixed4 frag(v2f i) : SV_TARGET {
				fixed3 tangentLightDir = normalize(i.lightDir);
				fixed3 tangetViewDir = normalize(i.viewDir);
				
				fixed3 tangentNormal = UnpackNormal(tex2D(_BumpMap,i.uv));
				tangentNormal.xy *= _BumpScale;
				tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy,tangentNormal.xy)));

				fixed3 albedo = tex2D(_MainTex,i.uv).rgb * _Color.rgb;
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
				fixed3 diffuse = _LightColor0.rbg * albedo * max(0,dot(tangentNormal,tangentLightDir));
				fixed3 halfDir = normalize(tangentLightDir + tangetViewDir);

				fixed specularMask = tex2D(_SpecularMask,i.uv).r * _SpecularScale;	// 获取遮罩值

				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0,dot(tangentNormal,halfDir)),_Gloss) * specularMask;  // 最后乘多一个遮罩值
				return fixed4(ambient + diffuse + specular,1.0);
			}
			ENDCG
		}
	}
	FallBack "Specular"
}
